Revealing the Synergistic Deactivation Mechanism of Hydrothermal Aging and SO Poisoning on Cu/SSZ-13 under SCR Condition.

In real-world application, Cu/SSZ-13 simultaneously suffers severe deactivation from hydrothermal aging and SO poisoning during the periodic regeneration of diesel particulate filter (DPF). Herein, we first investigated the synergistic deactivation mechanism of hydrothermal aging and SO poisoning on Cu/SSZ-13 under SCR condition. Hydrothermal aging alone induces more severe degradation of selective catalytic reduction (SCR) performance than SO poisoning alone, while the presence of SO during hydrothermal aging causes further worse SCR performance compared with hydrothermal aging alone. Hydrothermal aging not only damages Si-OH-Al sites, particularly in four-membered ring (4MR) of the CHA cage, but also brings the conversion of ZCuOH, leading to the formation of inactive CuO/CuAlO species. By contrast, SO poisoning alone is more prone to promote the transformation of ZCuOH to ZCu. Synergistic deactivation of hydrothermal aging and SO poisoning would exacerbate the damage of Si-OH-Al sites and then the formation of CuO/CuAlO species. These results are expected to assist the knowledge-based catalyst design for diesel aftertreatment applications.